TEMPERATURE 



299 



unequally. Of all substances, solid or liquid, water requires the 

 greatest amount of heat to change its temperature one degree. The 

 quantity of heat required to change the temperature of a unit mass 

 of any substance one degree is the specific heat of the substance. 

 Water is taken as unity. 



Specific Heats of Some Common Substances' 



This means that one pound of iron requires 0.119 as much heat 

 to change its temperature one degree as is required by a pound of 

 water, or that the heat necessary to effect a change of one degree in 

 a pound of water would raise 8.4 pounds of iron one degree, or one 

 pound 8.4 degrees. 



Dry soils generally possess a low specific heat, varying from 0.15 

 to 0.3, with an average of 0.215, or, in other words, it requires from 

 one-seventh to one-third as much heat to raise the temperature of dry 

 soil one degree as of water. 



Specific Heat of Soil Constituents 



The figures for peat vary a great deal, localise in some cases no 

 allowance was made for the heat of wetting. The specific heat of 

 equal volumes may be obtained by multiplying the specific heat of 

 equal weight by the specific gravity. 



